Iran should not have signed the 2015 international nuclear agreement, the military adviser to Supreme Leader Ayatollah Ali Khamenei said in a rare interview with the Western press airing Monday.

"I'm just following the viewpoints of my nation, the people of Iran," the official, Ali Shamkhani, told NBC News' Lester Holt, while claiming that there are many in his country who felt signing the agreement was a mistake.

Shamkhani is secretary of the Supreme National Security Council, making him Iran's top national security official. He is also a former anti-Shah militant and Revolutionary Guard member who once commanded Iran's naval forces, served as minister of defense and ran for president in 2001.

He also warned the United States to "act with wisdom" where his country is concerned and said the Trump sanctions policy will not bring it back to negotiate further on the nuclear deal.

"The sanctions campaign is not for negotiation, it's for making us surrender," Shamkhani said. "As long as this approach is taken by the United States, Iran will never ever seek negotiations."

But while Shamkhani said he thinks it was a mistake for his country to sign onto the JCPOA, he also wants to know why Trump pulled out of it in 2018.

All the same, the failure of the sanctions is obvious in Tehran, he told Holt, because one can see in the city "how energetic our people are and you will realize that [what the U.S. has] been trying to achieve has not materialized."

He also denied Iran is a sponsor of terror, but instead called Iranians who died fighting terrorist groups, like al-Qaida and ISIS, "martyrs."

However, he did not deny outright whether Iran has been behind the sabotage of oil tankers in the Strait of Hormuz, but said his country has been guaranteeing security. Still, Shamkhanii warned if there is war, the "already tarnished image of the United States will be even further destroyed in the region and the whole world. Why do they basically threaten to launch a war against us?"